The 28-year-old joined the Dublin-based outfit on a short-term deal in December and has impressed throughout his stint, putting in outstanding performances in both the United Rugby Championship and Champions Cup.
Barrett insists that he has "no regrets" about the experience and that being exposed to a different culture will serve him - and potentially the All Blacks - well going forward.
"You can't put your finger on one thing and say, 'look, that's a massive change, this is what I've learned', but there's little things within a working rugby week where Leinster's training structure might be a little bit different to that of the Hurricanes and the All Blacks," he told Sport Nation's Beaver & Guy show.
"There are certain things that I will see and go, 'I enjoy that, I think I will take that home with me.'
"There will also be things we'll be doing very similar up here to at home, and it's just good to have confirmation that these things are effective and they do work as well."
Leinster's Champions Cup hopes were ended at the semi-final stage by Northampton Saints, leaving the URC as their only hope for silverware this season.
Leo Cullen's men are heavy favourites for that competition, having finished at the top of the table with just two defeats in 18 matches.
Barrett admits that he has found the balancing act between the two the "biggest change" since moving to the northern hemisphere on his sabbatical.
"The biggest change for me is probably being in two different rugby competitions where you've got European opposition and then you've got your local domestic URC competition," he said.
"Just the preparation from week to week and how quickly it can change over a long season. The URC will go from September to late-June, whereas Super Rugby is a bit of a sprint, February to late-June.
"Particularly the size of the Leinster squad, where you're managing a big contingent of Irish internationals when they're available.
"When they're on Test duty, you're playing with a bunch of academy players who are good players in their own right but the dynamic changes week to week, so that's probably been the biggest change and learning for me."
Barrett also states that having to adapt week-on-week has been a challenge, given how varied the game can be in the United Rugby Championship and Champions Cup.
"That's probably been the biggest learning and growth area for me. For other players, coaches and systems up here, you've got to have a game and defensive system or attacking styles that are going to stand the test of time in different conditions against different opposition at a different time of the year.
"In practical terms, you could be playing up in Ulster on an artificial turf in two or three degrees, icy stadium in Belfast and then the next week you're playing a European game against a side like La Rochelle, who might have a 7-1 split and are just going to try and beat you up at a stadium that's sold out 100 successive times.
"You then jump on a plane and go to Pretoria back in the URC domestic comp and that's just the way the competition works.
"You've got to be able to adapt, learn quickly, change your focus and have a plan that you think is going to try and take you deep in both competitions.
"It's been great in that sense where it's refreshing to have different opposition in different conditions so you learn a few things."